The present invention relates to a nose cowl or spinner for a non-rotating shaft of a turbojet engine.
Turbojet engines typically have a central hub or shaft to support the various rotating and non-rotating components of the engine. A nose cowl or spinner is usually affixed to the forwardmost portion of this central hub or shaft to improve the aerodynamic efficiency of the air passing over the shaft and to efficiently direct the air into the turbojet engine with minimal perturbations. The nose cowl or spinner is symmetrical about the central longitudinal axis of the shaft and may define a curved or a generally pointed tip.
Such nose cowls or spinners may be attached to a rotating shaft of the turbojet engine so as to rotate with the shaft. An example of this type of cowl can be found in French Pat. No. 2,168,938 wherein a two-part cowl, joined together via a central, axial bolt, is fastened to the rotating shaft. Means are provided to direct warm or heated air into the space between the two cowl members so as to prevent ice from forming on the exterior surface of the cowl.
U.S. Pat. No. 4,405,208 to Surdi discloses a device for locking the turbine blades onto a fan wheel and also to attach a cowl thereto. The single piece cowl is adjoined to the rotating fan wheel via a bolt, which also assists in mounting the blades to the fan wheel.
U.S. Pat. No. 3,990,814 to Leone describes a spinner or nose cowl having a three-piece construction. The inner mounting member is attached to the fan hub and a frusto-conically shaped body member is attached to an upstream portion of this mounting member via bolts or the like. A nose piece or dome cap is attached to the forward ends of these elements by bolts or the like.
It is also known to attach a nose cowl or spinner to a stationary central hub or shaft of the turbojet engine as in French Pat. No. 2,253,922. The single piece nose cowl is attached to the central hub by a plurality of bolts or screws.
In the typical known structures, the outer surface of the nose cowl or spinner must define one or more access openings to allow access to the bolts or screws which attach it to the central hub or shaft. The presence of these indentations or openings formed in the external surface of the cowl create disturbances in the air flowing over the cowl and, hence, create perturbations in the air flowing into the turbojet engine. These perturbations affect the intake air flow and serve to decrease the efficiency of the turbojet engine compressor.
Solutions to this problem of the prior art devices have heretofore involved complex and inherently unreliable fastening methods to attach the nose cowl or spinner to the central hub. The solution result in an unduly complex attachment and detachment procedure, and do not provide a readily visible indication as to whether or not the nose cowl or spinner has been properly assembled to the central hub.